Polymeric dicyclopentadiene/limonene resin

ABSTRACT

This invention relates to a novel class of polymeric resins which have a softening point ranging from about 50° C. to about 220° C. and a molecular weight ranging from about 500 to about 42,000. The resins consist essentially of the polymers which result from the polymerization reaction between dicyclopentadiene and limonene. The polymeric resins are particularly useful in improving traction of the rubber when used in tire treads.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a polymeric resin which is the reactionproduct of the polymerization reaction between dicyclopentadiene andlimonene. Use of the polymeric resins of the present invention in arubber tire stock improves the traction and handling of the tire.

SUMMARY OF THE INVENTION

[0002] The present invention relates to a polymericdicyclopentadiene/limonene resin. The polymeric resins of the presentinvention have softening points ranging from about 50° C. to about 220°C., and a molecular weight of from about 500 to about 42,000. Thepresent invention also includes a blend of dicyclopentadiene/limoneneresins and rubber stocks containing the dicyclopentadiene/limoneneresin.

DETAILED DESCRIPTION OF THE INVENTION

[0003] The present invention relates to a polymeric resin consistingessentially of the reaction product of the polymerization reactionbetween dicyclopentadiene and limonene and having a softening pointranging from about 50° C. to about 220° C. and a molecular weightranging from about 500 to about 42,000.

[0004] In addition, the present invention relates to a resin compositioncomprising a blend of two or more polymeric resins wherein each resinconsists essentially of the reaction product of the polymerizationreaction between dicyclopentadiene and limonene. Alternatively, theblend can be formed in-situ; that is, the reaction temperature may beraised during the polymerization to increase the molecular weightdistribution and broaden the softening point.

[0005] In addition, there is disclosed a pneumatic tire having a treadcomprised of a rubber stock comprising (1) a rubber selected from thegroup consisting of natural rubber, rubber derived from a diene monomeror mixtures thereof, and (2) a polymeric resin composition consistingessentially of the reaction product of the polymerization reactionbetween dicyclopentadiene and limonene; said resin having a softeningpoint ranging from about 50 to about 220° C. and a molecular weightranging from about 500 to about 42,000.

[0006] There is also disclosed a rubber stock comprising (1) a rubberselected from the group consisting of natural rubber, rubber derivedfrom a diene monomer or mixtures thereof, and (2) a polymeric resincomposition consisting essentially of the reaction product of thepolymerization reaction between dicyclopentadiene and limonene; saidresin having a softening point ranging from about 50 to about 220° C.and a molecular weight ranging from about 500 to about 42,000.

[0007] The terms “polymeric compound” and “polymer” when used todescribe the resins of the present invention are intended to onlyinclude those molecules which contain a monomeric unit derived fromdicyclopentadiene and limonene and where at least one of the monomericunits derived from the dicyclopentadiene or limonene is repeated.Therefore, the compounds formed by the reaction of a singledicyclopentadiene molecule and a single limonene are not polymeric asthe term is used herein. The term monomeric unit means a structure thatoccurs in a polymeric compound and which differs from the structure ofdicyclopentadiene or limonene due to changes resulting from molecularreorientation during the linking to the adjacent structure. Thesechanges may include addition to a double bond or the addition or removalof a hydrogen atom from the dicyclopentadiene or limonene.

[0008] The molar ratio of the dicyclopentadiene to limonene in thepolymerization reaction may vary, depending on the desired properties ofthe final polymeric product. For example, the molar ratio of thedicyclopentadiene to limonene as starting material may range from about1:10 to about 10:1. The preferred molar ratio of dicyclopentadiene tolimonene may range from about 5:1 to 1:5 as starting material. The mostpreferred ratio ranges from about 2:1 to 1:2. As to the final product,the molar ratio of polymeric units derived from the dicyclopentadiene tolimonene may range from about 8:1 to 1:8. The preferred molar ratio ofdicyclopentadiene to limonene in the final product ranges from about 1:3to 3:1 with a range of from about 2.1:1 to 1:2.1, being particularlypreferred.

[0009] The polymerization reaction between the dicyclopentadiene may bea thermal (no catalyst) polymerization, or catalyzed, i.e., conducted inthe presence of an acid catalyst. Examples of acid catalysts that may beused include Bronsted acid and Lewis acid-type catalysts. Such knownacid catalysts include H₂SO₄, HCl, H₃PO₄; metal halides such as BF₃,BCl₃, AlCl₃, AlBr₃, SnCl₄, ZnCl₂, SbCl₃ and their etherates. The choiceof a particular catalyst is dependent upon factors including the meltingor boiling points of the reactants, desired rate of reaction, solvent,and pressure and temperature limitation of the production equipment,etc. When higher yields are desired, the metal halides or theiretherates may be utilized. The preferred acid catalysts are BF₃ andAlCl₃. The most preferred catalyst is AlCl₃.

[0010] In the catalyzed polymerization process, the amount of catalystmay range from about 0.1 to about 20 weight percent of catalyst based onthe total weight of reactants to be polymerized. Preferably, a range offrom about 3 to about 5 weight percent of catalyst is preferred. Theoptimum concentration of catalyst depends on the nature of the solvent,if any, which effects the solubility of the catalyst as well as on thestirring efficiency inside the polymerization reactor. High catalystconcentration reduces the resin molecular weight distribution and,therefore, limits the amount of feed additive required for controllingthe resin molecular weight.

[0011] The polymerization reaction may be carried out neat (withoutsolvent) at or above the melting points of the reactants, or can becarried out in the presence of a solvent. The solvent may be analiphatic C₆-C₁₂ hydrocarbon, an aromatic or haloaromatic (C₆-C₉)hydrocarbon, or a C₆-C₉ aliphatic halohydrocarbon. Examples of suitablesolvents include hexane, heptane, cyclohexane, benzene, toluene, xylene,and chlorobenzene. The preferred solvents are hexane and cyclohexane.

[0012] The polymerization reaction may be conducted under a variety ofoperating conditions. The reaction pressure may vary and range fromabout one atmosphere to about 100 atmospheres with a pressure of fromabout two atmospheres to about ten atmospheres being preferred. Thereaction temperature may range from about 0 to 100° C. with a preferredrange being from about 30 to 50° C.

[0013] Depending on the reactivity of the reactants, amount of catalyst,reaction pressure and reaction temperature, the reaction time may vary.Generally speaking, the reaction time varies from about 1 to about 8hours.

[0014] The molecular weight distribution of the polymeric resin of thepresent invention may range from about 500 to about 42,000. In aparticularly preferred embodiment of the present invention, the resincomposition comprises a blend of two or more individual polymeric resinseach one of which is the reaction product of a polymerization reactionbetween dicyclopentadiene and limonene. Each individual polymeric resinpreferably differs from the other by having a different molecular weightrange. Generally speaking, all of the polymeric resins will exhibit somelower molecular weight values, however, not all of the individual resinsmay include the higher molecular values. In the alternative, all of theresins may have distributions that vary by their lower molecular valueswith the high molecular weight value relatively being the same. Forexample, when the resin blend comprises three individual polymericresins, the first resin may have a molecular weight ranging from about700 to about 24,000, the second resin may have a molecular weightranging from about 700 to about 36,000, and the third resin may have amolecular weight ranging from about 700 to about 42,000.

[0015] In accordance to another embodiment of the present invention, theresin composition may comprise a blend of four individual resins. Inaccordance with this embodiment, the first resin may have a molecularweight ranging from about 500 to about 15,000, the second resin may havea molecular weight ranging from about 700 to about 15,000, the thirdresin may have a molecular weight ranging from about 3,000 to about15,000, and the fourth resin may have a molecular weight ranging fromabout 4,000 to about 15,000.

[0016] The blend may be formed in-situ or mechanically blended.

[0017] The resin composition of the present invention has a softeningpoint ranging from about 50 to about 220. For the purposes of thepresent invention, the term “softening point” is used to describe thetemperature range from when wetting occurs in a capillary melting pointtube to where the resin is completely liquid. Representative of suitableequipment to determine the relative softening point is a Thomas-HooverMelting Point apparatus equipped with a silicon oil bath. In accordancewith the embodiment of the present invention when the resin compositioncomprises a blend of three individual resins, the first resin may have asoftening point ranging from about 134 to about 156° C., the secondresin may have a softening point ranging from about 138 to about 180°C., and the third resin may have a softening point ranging from about188 to about 208° C. In accordance with the embodiment of the presentinvention where the blend comprises four individual resins, the firstresin may have a softening point ranging from about 55 to about 75° C.,the second resin may have a softening point ranging from about 80 toabout 131° C., the third resin may have a softening point ranging fromabout 126 to about 168° C., and the fourth resin may have a softeningpoint range of about 168 to about 195° C.

[0018] Rubber stocks containing natural rubber or rubbers derived from adiene monomer may be modified with the resin compositions of the presentinvention. Examples of rubbers derived from a diene monomer includesubstituted and unsubstituted, saturated and unsaturated, syntheticpolymers. The natural polymers include natural rubber in its variousforms, e.g., pale crepe and smoked sheet, and balata and gutta percha.The synthetic polymers include those prepared from a single monomer(homopolymer) or a mixture of two or more copolymerizable monomers(copolymer) when the monomers are combined in the random distribution orblock form. In addition to the diene monomers, other monomers may beused. Of all the monomers that may be used, the monomers may besubstituted or unsubstituted and may possess one or more double bonds,for example, diene monomers, both conjugated and nonconjugated, andmonoolefins, including cyclic and acyclic monoolefins, especially vinyland vinylidene monomers. Examples of conjugated dienes are1,3-butadiene, isoprene, chloroprene, 2-ethyl-1,3-butadiene,2,3-dimethyl-1,3-butadiene and piperylene. Examples of nonconjugateddienes are 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene,dicyclopentadiene, 1,5-cyclooctadiene and ethylidene norbornene.Examples of acyclic monoolefins are ethylene, propylene, 1-butene,isobutylene, 1-pentene and 1-hexene. Examples of cyclic monoolefins arecyclopentene, cyclohexene, cycloheptene, cyclooctene and4-methyl-cyclooctene. Examples of vinyl monomers are styrene,acrylonitrile, acrylic acid, ethylacrylate, vinyl chloride,butylacrylate, methyl vinyl ether, vinyl acetate and vinyl pyridine.Examples of vinylidene monomers are alpha-methylstyrene, methacrylicacid, methyl methacrylate, itaconic acid, ethyl methacrylate, glycidylmethacrylate and vinylidene chloride. Representative examples of thesynthetic polymers used in the practice of this invention arepolychloroprene, homopolymers of a conjugated 1,3-diene such as isopreneand butadiene, and in particular, polyisoprenes and polybutadieneshaving essentially all of their repeat units combined in acis-1,4-structure; and copolymers of a conjugated 1,3-diene such asisoprene and butadiene with up to 50 percent by weight of at least onecopolymerizable monomer, including ethylenically unsaturated monomerssuch as styrene or acrylonitrile; and butyl rubber, which is apolymerization product of a major proportion of a monoolefin and a minorproportion of a diolefin such as butadiene or isoprene.

[0019] The rubber compounds which may be modified by the resins of thepresent invention are preferably cis-1,4-polyisoprene (natural orsynthetic), polybutadiene, polychloroprene and the copolymers ofisoprene and butadiene, copolymers of acrylonitrile and butadiene,copolymers of acrylonitrile and isoprene, copolymers of styrene,butadiene and isoprene, copolymers of styrene and butadiene and blendsthereof.

[0020] The amount of polymeric resins that may be used with the dienecontaining polymers may vary and depend on the polymer to be modified,the particular polymeric resin, the desired degree of modification andthe like. Generally speaking, the polymeric resin is used in amountsranging from about 5 to about 50 parts per hundred (phr) of dienepolymer. Preferably, the polymeric resin is used in amounts of fromabout 5 to about 25 phr, with a range of from about 10 to about 25 phrbeing particularly preferred.

[0021] The polymeric resins may be incorporated in the diene containingpolymer by conventional mixing procedures, for example, by adding themin a banbury mixer or by adding them to the rubber on a mill.Preferably, when the polymeric resins have higher molecular weights, itis recommended that they be ground to a fine powder to insure adequatedispersion. Such powders may be treated to suppress dust, for example,by the addition of oil, or they can be mixed with a binder, for example,a polymer latex, and granules or pellets containing up to 5 percent byweight of a binder. They can also be formulated as pre-dispersions ormasterbatched in a diene rubber stock, which pre-dispersions maycontain, for example, from 15 to 50 percent by weight of the polymericresin.

[0022] Similar to vulcanizing conventional rubber stocks, the rubberstocks containing the polymeric resins need a sulfur vulcanizing agent.Examples of suitable sulfur vulcanizing agents include elemental sulfur(free sulfur) or sulfur donating vulcanizing agents, for example, anamine disulfide, polymeric polysulfide or sulfur olefin adducts.Preferably, the sulfur vulcanizing agent is elemental sulfur. The amountof sulfur vulcanizing agent will vary depending on the components of therubber stock and the particular type of sulfur vulcanizing agent that isused. Generally speaking, the amount of sulfur vulcanizing agent rangesfrom about 0.1 to about 8 phr with a range of from about 1.5 to about 6being preferred.

[0023] Conventional rubber additives may be incorporated in the rubberstock of the present invention. The presence of a sulfur vulcanizingagent and conventional additives are not considered to be an aspect ofthis invention. The additives commonly used in rubber stocks includefillers, plasticizers, curatives, processing oils, retarders,antiozonants, antioxidants and the like. The total amount of filler thatmay be used may range from about 45 to about 130 phr being preferred.Fillers include silicas, clays, calcium carbonate, calcium silicate,titanium dioxide and carbon black. Preferably, at least a portion of thefiller is carbon black. Plasticizers, oils or mixtures thereof areconventionally used in amounts ranging from about 2 to about 150 phrwith a range of about 5 to about 130 phr being preferred. The amount ofplasticizer used will depend upon the softening effect desired. Examplesof suitable plasticizers include aromatic extract oils, petroleumsofteners including asphaltenes, saturated and unsaturated hydrocarbonsand nitrogen bases, coal tar products, cumarone-indene resins and esterssuch as dibutylphthalate and tricresyl phosphate. Examples of oils arecommonly known as highly aromatic process oil, process soybean oil andhighly paraffinic process oil. Materials used in compounding whichfunction as an accelerator-activator includes metal oxides such as zincoxide, magnesium oxide and litharge which are used in conjunction withacidic materials such as fatty acid, for example, stearic acid, oleicacid, murastic acid, and the like. The amount of the metal oxide mayrange from about 1 to about 10 phr with a range of from about 2 to about8 phr being preferred. The amount of fatty acid which may be used mayrange from about 0.25 phr to about 5.0 phr with a range of from about0.5 phr to about 2 phr being preferred.

[0024] Accelerators may be used to control the time and/or temperaturerequired for vulcanization of the rubber stock. As known to thoseskilled in the art, a single accelerator may be used which is present inamounts ranging from about 0.2 to about 3.0 phr. In the alternative,combinations of two or more accelerators may be used which consist of aprimary accelerator which is generally used in a larger amount (0.3 toabout 3.0 phr), and a secondary accelerator which is generally used insmaller amounts (0.05 to about 1.50 phr) in order to activate andimprove the properties of the rubber stock. Combinations of theseaccelerators have been known to produce synergistic effects on the finalproperties and are somewhat better than those produced by use of eitheraccelerator alone. Delayed action accelerators also are known to be usedwhich are not affected by normal processing temperatures and producesatisfactory cures at ordinary vulcanization temperatures. Suitabletypes of accelerators include amines, disulfides, guanidines, thioureas,thiazoles, thiurams, sulfenamides, dithiocarbamates and the xanthates.Examples of specific compounds which are suitable include zincdiethyl-dithiocarbamate, 4,4′-dithiodimorpholine,N,N-di-methyl-S-tert-butylsulfenyldithiocarbamate, tetramethylthiuramdisulfide, 2,2′-dibenzothiazyl disulfide, butyraldehydeanilinemercaptobenzothiazole, N-oxydiethylene-2-benzothiazolesulfenamide.Preferably, the accelerator is a sulfenamide.

[0025] A class of compounding materials known as scorch retarders arecommonly used. Phthalic anhydride, salicyclic acid, sodium acetate andN-cyclohexyl thiophthalimide are known retarders. Retarders aregenerally used in an amount ranging from about 0.1 to 0.5 phr.

[0026] Preformed phenol-formaldehyde type resins may be used in therubber stock and are generally present in an amount ranging from about1.0 to about 5.0 phr, with a range of from about 1.5 to about 3.5 phrbeing preferred.

[0027] Conventionally, antioxidants and some times antiozonants,hereinafter referred to as antidegradants, are added to rubber stocks.Representative antidegradants include monophenols, bisphenols,thiobisphenols, polyphenols, hydroquinone derivatives, phosphites,thioesters, naphthyl amines, diphenyl-p-phenylenediamines,diphenylamines and other diaryl amine derivatives,para-phenylenediamines, quinolines and mixtures thereof. Specificexamples of such antidegradants are disclosed in The Vanderbilt RubberHandbook (1990), pages 282-286. Antidegradants are generally used inamounts from about 0.25 to about 5.0 phr with a range of from about 1.0to about 3.0 phr being preferred.

[0028] The mixing of the rubber composition can be accomplished bymethods known to those having skill in the rubber mixing art. Forexample, the ingredients are typically mixed in at least two stages;namely, at least one non-productive stage followed by a productive mixstage. The final curatives including sulfur vulcanizing agents aretypically mixed in the final stage which is conventionally called the“productive” mix stage in which the mixing typically occurs at atemperature, or ultimate temperature, lower than the mix temperature(s)than the preceding non-productive mix stage(s). The rubber and polymericresin are mixed in one or more non-productive mix stages. The terms“non-productive” and “productive” mix stages are well known to thosehaving skill in the rubber mixing art.

[0029] Vulcanization of the pneumatic tire of the present invention isgenerally carried out at conventional temperatures ranging from about100° C. to 200° C. Preferably, the vulcanization is conducted attemperatures ranging from about 110° C. to 180° C. Any of the usualvulcanization processes may be used such as heating in a press or mold,heating with superheated steam or hot air or in a salt bath.

[0030] The following examples are presented in order to illustrate butnot limit the present invention.

[0031] Cure properties were determined using a Monsanto oscillating discrheometer which was operated at a temperature of 150° C. and at afrequency of 11 hertz. A description of oscillating disc rheometers canbe found in the Vanderbilt Rubber Handbook edited by Robert O. Ohm(Norwalk, Conn., R. T. Vanderbilt Company, Inc., 1990), pages 554-557.The use of this cure meter and standardized values read from the curveare specified in ASTM D-2084. A typical cure curve obtained on anoscillating disc rheometer is shown on page 555 of the 1990 edition ofthe Vanderbilt Rubber Handbook.

[0032] In such an oscillating disc rheometer, compounded rubber samplesare subjected to an oscillating shearing action of constant amplitude.The torque of the oscillating disc embedded in the stock that is beingtested that is required to oscillate the rotor at the vulcanizationtemperature is measured. The values obtained using this cure test arevery significant since changes in the rubber or the compounding recipeare very readily detected. It is obvious that it is normallyadvantageous to have a fast cure rate.

[0033] In the following examples, the Flexsys Rubber Process Analyzer(RPA) 2000 was used to determine dynamic mechanical rheologicalproperties. The curing conditions were 160° C., 1.667 Hz, 15.8 minutesand 0.7 percent strain. A description of the RPA 2000, its capability,sample preparation, tests and subtests can be found in these references.H A Pawlowski and J S Dick, Rubber World, June 1992; J S Dick and H APawlowski, Rubber World, January 1997; and J S Dick and J A Pawlowski,Rubber & Plastics News, Apr. 26 and May 10, 1993.

[0034] The compounded rubber sample is placed on the bottom die. Whenthe dies are brought together, the sample is in a pressurized cavitywhere it will be subjected to a sinusoidal oscillating shearing actionof the bottom die. A torque transducer connected to the upper diemeasures the amount of torque transmitted through the sample as a resultof the oscillations. Torque is translated into the shear modulus, G, bycorrecting for the die form factor and the strain. The RPA 2000 iscapable of testing uncured or cured rubber with a high degree ofrepeatability and reproducibility. The tests and subtests availableinclude frequency sweeps at constant temperature and strain, curing atconstant temperature and frequency, strain sweeps at constanttemperature and frequency and temperature sweeps at constant strain andfrequency. The accuracy and precision of the instrument allowsreproducible detection of changes in the compounded sample.

[0035] The values reported for the storage modulus, (G′), losscompliance (J″) and tan delta are obtained from a strain sweep at 100°C. and 1 Hz following the cure test. These properties represent theviscoelastic response of a test sample to shear deformation at aconstant temperature and frequency.

[0036] The following examples are presented for the purposes ofillustrating and not limiting the present invention. All parts are partsby weight unless specifically identified otherwise.

EXAMPLE 1

[0037] A one liter stainless steel autoclave was charged with 170 gramsof washed and dried dicyclopentadiene, 80 grams of washed and dried(+)-limonene and 100 milliliters of xylenes. The reactor was flushedwith nitrogen, sealed and heated to 270° C. with stirring. The reactorpressure peaked at 185 psig at 270° C. The reactor pressure began todrop as the temperature was maintained at 270° C. Within about 15minutes, the pressure dropped 20 to 30 psig. After one hour of residencetime, the reactor was cooled. The contents were transferred to a flaskand heated to about 170° C., and the pressure on the surface of thecontents was reduced to about 25 inches of mercury vacuum. The strippedresin was poured from the flask as molten material at about 150° C. Asoftening point from 55-75° C. was determined. The molecular weightrange was determined to be 500 to 15,000.

EXAMPLE 2

[0038] The procedures of Example 1 were repeated except the residencetime at 270° C. was two hours, instead of one hour. The softening pointfor this polymeric resin ranged from about 80 to 131° C. The molecularweight range was determined to be 700 to 15,000.

EXAMPLE 3

[0039] The procedures of Example 1 were repeated, except the residencetime at 270° C. was 4 hours, and the polymeric resin product had asoftening point ranging from about 126° C. to 168° C. The molecularweight range was determined to be 3,000 to 15,000.

EXAMPLE 4

[0040] The procedures of Example 1 were repeated except the residencetime of 270° C. was for 6 hours instead of one hour, and the softeningpoint for the resin ranged from about 168° C. to 195° C. The molecularweight range was determined to be 4,000 to 15,000.

EXAMPLE 5

[0041] The dicyclopentadiene/limonene resin from Examples 1-4, werecombined by mixing 150 grams of each polymeric resin into a 2-literstainless steel beaker. A hot plate was used to melt the polymericresins and stirring gave a homogeneous mixture. The blend was cooled toroom temperature, and chipped into small granular pieces, whichexhibited an overall softening range of from about 78 to 173° C. Theproduct was an amber-color solid.

EXAMPLE 6

[0042] A three liter round bottom flask was fitted with a mechanicalstirrer, a constant temperature water bath, a thermocouple and adropping funnel. The flask was swept with nitrogen and charged with 200milliliters of cyclohexane containing 10 grams of anhydrous aluminumchloride. Stirring was started and the water bath raised the temperatureof the aluminum chloride/cyclohexane suspension to 30° C. The droppingfunnel was charged with a 170 grams of dicyclopentadiene that had beenwashed with 6 percent aqueous sodium hydroxide inhibitor, but not driedafter a second washing with water, 80 grams of (+)-limonene of technicalgrade from Eastman Kodak and 100 milliliters of cyclohexane. The feedstream was added as quickly as possible with the reaction temperaturemaintained at 32±2° C. After about 25 minutes, all of the feed had beenadded and the reaction temperature of 32±2° C. was maintained for threehours with stirring. A solution of 200 milliliters of isopropanol and600 milliliters of water was added to the reaction mixture as the heatwas removed. The aqueous-organic mixture was stirred vigorously untilall of the catalyst had been hydrolyzed. The organic layer whichcontains a suspended solid was separated and washed with two portions of200 milliliters of water. The organic layer which contained thesuspended solid was dried in a drying oven at 150° C. and 28 inches ofmercury vacuum. The product softens or shows wetting in a capillarymelting point tube at 188 to about 208° C. with a molecular weight rangeof 700 to 40,000.

EXAMPLE 7

[0043] The reaction conditions and procedures of Example 6 were repeatedat 42±2° C. to give a resin that softens or shows wetting in a capillarymelting tube at 138 to 180° C. with a molecular weight range of 700 to36,000.

EXAMPLE 8

[0044] Reaction conditions and procedures of Example 6 were repeatedexcept the reaction was conducted at 52±2° C. to give a resin thatsoftens or shows wetting in a capillary melting point tube at 134 to156° C. with a molecular weight range of 700 to 24,000.

EXAMPLE 9

[0045] The dicyclopentadiene/limonene resin from Examples 6, 7, and 8were combined by mixing 75 grams of each polymeric resin into a 2-literstainless steel beaker. A hot plate was used to liquify the polymericresins and stirring gave a homogeneous mixture. The blend was cooled toroom temperature, and chipped into small granular pieces, whichexhibited an overall softening range of from 132° C. to 191° C.

EXAMPLE 10

[0046] Three hundred parts of cyclohexane and 50 parts of anhydrousaluminum chloride were placed into a reactor. While continuouslystirring the mixture, 600 parts of a hydrocarbon mixture was slowlyadded to the reactor over a period of about 60 minutes. The hydrocarbonmixture consisted of 30 percent inert hydrocarbons with the remaining 70percent by weight of the mixture comprising the following resin formingcomponents: Component Percent Limonene 67.0 Dicyclopentadiene 33.0

[0047] The temperature of the reaction was maintained in a range ofabout 250 to 30° C. After an hour of agitation from the time of finaladdition, the hydrocarbon mixture was added to approximately 4,000 partsof a 25 percent solution of isopropyl alcohol in water to neutralize anddecompose the aluminum chloride. The aqueous layer was removed and theresin solution washed with an additional 4,000 parts of thealcohol/water blend.

[0048] The resulting resin solution was steam-distilled at a pottemperature of about 235° C. The resulting residual molten resin wascooled to room temperature to provide an 85 percent yield of a hardbrittle pale yellow resin having a softening point of 110° C. to 129° C.Small molecule GPC analysis gives a molecular weight distribution of 6.7percent in the 9500 MW range, 69.1 percent in the 1100 MW range, 6.5percent in the 600 MW range, 9.0 percent in the 450 MW range and 4.6percent in the 330 MW range.

EXAMPLE 11

[0049] A rubber stock was prepared which consisted of styrene butadienerubber and conventional amounts of carbon black antioxidant, sulfur andaccelerator, fatty acid and zinc oxide. In addition, each samplecontained a highly aromatic processing oil, highly paraffinic processoil and processed soybean oil. In Samples 1 and 3, the three oils werepartially replaced with a polymeric dicyclopentadiene/limonene resin. Inthis study, each of the four polymeric resins prepared in accordancewith Examples 1-4 was used at the 6 and 12 phr level (total resin was 24and 48 phr) and compared with the control compounds. The table belowprovides the relative amounts of the various oils and resins. Inaddition, the properties of each of the resulting rubber stocks weretested nd are listed in the table. The cured specimens of each rubberstock were prepared by press curing the sample at 150° C. for 28 minutesunder 280 psi pressure with the exception of those specimens used totest for Strebler, Zwick Rebound, Light Blow Out and DIN Abrasion. Thesamples for testing for Strebler, Zwick Rebound and Light Blow Out werecured for 38 minutes. The specimens tested for DIN Abrasion were curedfor 33 minutes. TABLE I Sample 1 2 3 4 Aromatic Processing Oil 22.0030.00 14.00 30.00 Paraffinic Processing Oil 22.00 30.00 14.00 30.00Process Soybean Oil 22.00 30.00 14.00 30.00 Example 1 Resin 6.00 12.00Example 2 Resin 6.00 12.00 Example 3 Resin 6.00 12.00 Example 4 Resin6.00 12.00 Productive Tests: Rheometer MDR2000 @ 150° C. S′Min (dN-m)2.7 2.4 3.1 2.6 T (1) 5.1 4.7 5.4 5.0 TC25 5.8 5.4 6.3 5.7 TC90 25.518.4 32.4 18.1 S′Max (dN-m) 10.0 10.1 10.4 10.5 Delta S′ (dN-m) 7.3 7.47.2 8.0 S″ @ S′MaX 2.7 2.1 3.2 2.4 TanD @ S′Max 0.27 0.21 0.31 0.23Assigned Cures 28 28 28 28 Stress Strain 300% Modulus (MPa) 3.2 4.4 3.24.8 Tensile (MPa) 7.9 10.0 7.2 7.6 Elongation (%) 684 636 706 468Rebound RT 11.5 12.1 12.7 12.5 100° C. 20.8 29.3 17.3 30.0 Hardness RT66.3 59.4 74.7 59.7 100° C. 39.1 40.1 44.5 41.3 Strebler Normalized to0.2″ Avg Force (N) 105 154 106 N/A 110 143 121 N/A Zwick Rebound 65° C.15.8 20.0 14.2 17.4 95° C. 19.0 25.0 14.8 23.8 120° C. 22.6 31.0 17.830.6 150° C. 28.0 37.8 24.2 36.8 Light Blow Out Temp (F.) 319 310 362307 Time (Min) 23 27.5 18 15 DIN Abrasion Rating 274 279 282 278 MTSDynamic Modulus E′ (MPa) 5.8 5.4 7.0 6.0 Tan Delta 0.45 0.39 0.48 0.40Autovibron at 60° C. E′ (MPa) 20.8 16.5 40.9 15.1 E″ (MPa) 4.2 2.9 6.12.5 Tangent Delta 0.19 0.18 0.15 0.17 Autovibron at 100° C. E′ (MPa)11.8 9.6 17.5 9.0 E″ (MPa) 3.2 1.6 3.5 1.4 Tangent Delta 0.19 0.17 0.200.16 Autovibron at 150° C. E′ (MPa) 10.4 8.0 14.1 7.5 E″ (MPa) 1.8 1.12.7 .9 Tangent Delta 0.17 0.13 0.19 0.13

[0050] As one can see from the above data, the effect of using thedicyclopentadiene/limonene resins in place of the aromatic processingoil, paraffinic processing oil and processed soybean oil was to increasethe hysteresis (rebound, E″, tangent delta) and low strain stiffness(E′, hardness) while reducing the cure state (300 percent modulus), curerate (T25, T90) and tear (Strebler). The dicyclopentadiene/limoneneresins gave better storage modulus, loss modulus and tangent deltathroughout the temperature range of 60° C. to 150° C. It is thisresponse with temperature that provides enhanced traction and handling.

EXAMPLE 12

[0051] In this example, various resins were evaluated in a rubbercompound.

[0052] Rubber compositions containing the materials set out in Tables 2and 3 were prepared in a BR Banbury™ mixer using two separate stages ofaddition (mixing); namely, one non-productive mix stage and oneproductive mix stage. The non-productive stage was mixed for 3.5 minutesor to a rubber temperature of 160° C., whichever occurred first. Themixing time for the productive stage was to a rubber temperature of 120°C.

[0053] The rubber compositions are identified herein as Samples 1-3.Samples 1 and 2 are considered herein as controls without the use of theresin used in the present invention being added to the rubbercomposition. Samples 1 and 2 each contain commercially available resins.Sample 3 is the resin prepared in Example 10.

[0054] The samples were cured at about 150° C. for about 28 minutes.

[0055] Table 3 illustrates the behavior and physical properties of thecured Samples 1-3.

[0056] Lab data reveals that the new DCPD/Limonene resin in factenhances the traction and durability properties simultaneously withoutfollowing the typical tradeoff as previously described. Comparing thedynamic properties from the RPA 2000 and stress-strain data (UTS) of theCoumarone-Indene and phenolic resins, the typical tradeoff ofsacrificing durability (lower G′ at 40 percent strain, 300 percentmodulus and tensile strength) for improved dry traction (increased tandelta and loss compliance at 40 percent strain) is demonstrated. ControlA (phenolic resin) is a soft compound with high hysteresis. Control B(Coumarone-Indene resin) is a stiff compound with low hysteresis.

[0057] The DCPD/Limonene resin versus the Control A shows that thedurability is significantly improved (G′ at 40 percent strain, 300percent modulus and tensile strength) and dry traction is maintained(tan delta and J″ at 40 percent). Control B represents a typical effortto increase the durability of Control A through the use of resins. TheDCPD/Limonene resin versus the Control B shows that the durability isonly slightly reduced (G′ at 40 percent strain, 300 percent modulus andtensile strength) and the dry traction is significantly improved (tandelta and J″ at 40 percent). TABLE 2 Ctrl Ctrl Samples 1 2 3Non-Productive Emulsion SBR¹ 100 100 100 Carbon Black² 80.0 80.0 80.0Aromatic Oil 37.5 37.5 37.5 Stearic Acid 2.0 2.0 2.0 MicrocrystallineWax 2.0 2.0 2.0 Zinc Oxide 3.0 3.0 3.0 Antioxidant³ 1.0 1.0 1.0 PhenolicResin⁴ 25.0 0 0 Coumarone Indene⁵ Resin 0 25.0 0 Resin of Example 10 0 025.0 Productive Accelerators⁶ 3.5 3.5 3.5 Accelerator⁷ 0.25 0.25 0.25Sulfur 0.95 0.95 0.95

[0058] TABLE 3 Sample 1 2 3 Phenolic resin 25.0 0 0 Coumarone IndeneResin 0 25.0 0 Resin of Example 10 0 0 25.0 RPA 2000, 15.8 min, 160° C.,17% strain, 1.67 Hz T25 (min) 1.89 2.98 1.92 T90 (min) 9.3 9.7 9.7 MinTorque (dNm) 0.49 0.59 0.66 Max Torque (dNm) 1.76 2.28 2.28 Delta Torque(dNm) 1.27 1.69 1.62 RPA 2000, 1 Hz, 100° C. G′ 40% (KPa) 376 476 449Tan Delta 40% 0.254 0.224 0.277 J″ 40% 1/MPa 0.63 0.45 0.57 UTS, cure 28minutes @ 150° C. 300% Modulus, MPa 3.5 4.1 3.6 Tensile Strength, MPa13.2 15.8 14.7 Elongation, % 719 718 740 Zwick Rebound, 95° C. 29.8 35.629.8 Rebound 120° C. 35.8 40.6 34

What is claimed is:
 1. A resin composition consisting essentially of apolymer which is the reaction product of the polymerization reactionbetween dicyclopentadiene and limonene, said resin having a softeningpoint ranging from about 50 to about 220° C. and a molecular weightranging from about 500 to about 42,000.
 2. A resin compositioncomprising a blend of two or more resins, wherein each resin consistsessentially of the polymer which is the reaction product of thepolymerization reaction between dicyclopentadiene and limonene and eachresin has a is softening point ranging from about 50 to about 220° C.and a molecular weight ranging from about 500 to about 42,000.
 3. Theresin composition of claim 1 wherein the blend comprises four individualresins.
 4. The resin composition of claim 2 wherein said blend comprisesthree individual resins.
 5. The resin composition of claim 1 whereinsaid composition consists essentially of the polymerization reactionproduct of from about 10 to about 1 moles of dicyclopentadiene and fromabout 1 to about 10 moles of limonene.
 6. The resin composition of claim2 wherein each resin is the polymerization reaction product of fromabout 1 to about 2 moles of dicyclopentadiene and from about 2 to about1 moles of limonene.
 7. The resin composition of claim 3 wherein thefirst resin has a softening point ranging from about 55 to about 75° C.,the second resin has a softening point ranging from about 80 to about131° C., the third resin has a softening point ranging from about 126 toabout 168° C., and the fourth resin has a softening point ranging fromabout 168 to about 195° C.
 8. The resin composition of claim 4 whereinthe first resin has a softening point ranging from about 134 to about156° C., the second resin has a softening point ranging from about 138to about 180° C., and the third resin has a softening point ranging fromabout 188 to about 208° C.
 9. The resin composition of claim 3 whereinthe first resin has a molecular weight ranging from about 500 to about15,000, the second resin has a molecular weight ranging from about 700to about 15,000, the third resin has a molecular weight ranging fromabout 3,000 to about 15,000, and the fourth resin has a molecular weightranging from about 4,000 to about 15,000.
 10. The resin composition ofclaim 4 wherein the first resin has a molecular weight ranging fromabout 700 to about 24,000, the second resin has a molecular weightranging from about 700 to about 36,000, and the third resin has amolecular weight ranging from about 700 to about 42,000.
 11. The resincomposition of claim 1 wherein said polymerization is conducted in thepresence of a catalyst.
 12. The resin composition of claim 11 whereinsaid catalyst is selected from the group consisting of H₂SO₄, HCl,H₃PO₄, HClO₄, BF₃, BCl₃, AlCl₃, AlBr₃, SnCl₄, ZnCl₂, SbCl₃, andetherates of said acid catalyst.
 13. The resin composition of claim 1wherein said polymerization is a thermal polymerization.
 14. A rubberstock comprising (1) a rubber selected from the group consisting ofnatural rubber, rubbers derived from a diene monomer or mixturesthereof, and (2) a polymeric resin composition consisting essentially ofthe reaction product of the polymerization between dicyclopentadiene andlimonene, said resin having a softening point ranging from about 50 toabout 220° C., and an average molecular weight ranging from about 500 toabout 42,000.
 15. The rubber stock of claim 14 wherein said rubberderived from a diene monomer or mixtures thereof is selected from thegroup comprising natural rubber, polyisoprene, polybutadiene,polychloroprene, copolymers of isoprene and butadiene, copolymers ofstyrene and butadiene, copolymers of acrylonitrile and butadiene,copolymers of acrylonitrile and isoprene and blends thereof.
 16. Therubber stock of claim 14 wherein said polymeric resin composition ispresent in an amount ranging from about 5 to about 50 parts per hundredparts of rubber.
 17. The rubber stock of claim 16 wherein said polymericresin composition is present in an amount ranging from about 10 to about25 parts per hundred parts of rubber.
 18. The rubber stock of claim 14wherein the resin composition comprises a blend of four individualresins.
 19. The rubber stock of claim 14 wherein said resin compositioncomprises a blend of three individual resins.
 20. The rubber stock ofclaim 18 wherein the first resin has a softening point ranging fromabout 55 to about 75° C., the second resin has a softening point rangingfrom about 80 to about 131° C., the third resin has a softening pointranging from about 126 to about 168° C., and the fourth resin has asoftening point ranging from about 168 to about 195° C.
 21. The rubberstock of claim 19 wherein the first resin has a softening point rangingfrom about 135 to about 156° C., the second resin has a softening pointranging from about 138 to about 180° C., and the third resin has asoftening point ranging from about 188 to about 208° C.
 22. The rubberstock of claim 18 wherein the first resin has a molecular weight rangingfrom about 500 to about 15,000, the second resin has a molecular weightranging from about 700 to about 15,000, the third resin has a molecularweight ranging from about 3,000 to about 15,000, and the fourth resinhas a molecular weight ranging from about 4,000 to about 15,000.
 23. Therubber stock of claim 19 wherein the first resin has a molecular weightranging from about 700 to about 24,000, the second resin has a molecularweight ranging from about 700 to about 36,000, and the third resin has amolecular weight ranging from about 700 to about 42,000.
 24. A pneumatictire having a tread comprised of (1) a rubber selected from the groupconsisting of natural rubber, rubbers derived from a diene monomer ormixtures thereof, and (2) a polymeric resin composition consistingessentially of the reaction product of the polymerization betweendicyclopentadiene and limonene, said resin having a softening pointranging from about 50 to about 220° C., and an average molecular weightranging from about 500 to about 42,000.
 25. The pneumatic tire of claim24 wherein said rubber derived from a diene monomer or mixtures thereofis selected from the group comprising natural rubber, polyisoprene,polybutadiene, polychloroprene, copolymers of isoprene and butadiene,copolymers of styrene and butadiene, copolymers of acrylonitrile andbutadiene, copolymers of acrylonitrile and isoprene and blends thereof.26. The pneumatic tire of claim 24 wherein said polymeric resincomposition is present in an amount ranging from about 5 to about 50parts per hundred parts of rubber.
 27. The pneumatic tire of claim 26wherein said polymeric resin composition is present in an amount rangingfrom about 10 to about 25 parts per hundred parts of rubber.
 28. Thepneumatic tire of claim 24 wherein the resin composition comprises ablend of four individual resins.
 29. The pneumatic tire of claim 24wherein said resin composition comprises a blend of three individualresins.
 30. The pneumatic tire of claim 28 wherein the first resin has asoftening point ranging from about 55 to about 75° C., the second resinhas a softening point ranging from about 80 to about 131° C., the thirdresin has a softening point ranging from about 126 to about 168° C., andthe fourth resin has a softening point ranging from about 168 to about195° C.
 31. The pneumatic tire of claim 29 wherein the first resin has asoftening point ranging from about 135 to about 156° C., the secondresin has a softening point ranging from about 138 to about 180° C., andthe third resin has a softening point ranging from about 188 to about208° C.
 32. The pneumatic tire of claim 28 wherein the first resin has amolecular weight ranging from about 500 to about 15,000, the secondresin has a molecular weight ranging from about 700 to about 15,000, thethird resin has a molecular weight ranging from about 3,000 to about15,000, and the fourth resin has a molecular weight ranging from about4,000 to about 15,000.
 33. The pneumatic tire of claim 29 wherein thefirst resin has a molecular weight ranging from about 700 to about24,000, the second resin has a molecular weight ranging from about 700to about 36,000, and the third resin has a molecular weight ranging fromabout 700 to about 42,000.